安装与配置Hadoop出现的常见问题

1.当链接ssh服务器端，ssh localhost出现错误“ssh: connect to host localhost port 22: Connection refused”时，这个有可能是你删除了ssh链接的用户名。如果已经删除了，重装可以解决问题。但是cygrunsrv -R sshd移除ssh服务后，再重新ssh-host-config配置时，总是提示你已经安装了ssh，而无法继续向下安装。如此陷入循环，这时可以尝试在注册表(我安装的都是在Win32+Cygwin)中删除ssh相关目录，然后再重启机器重新安装。

2.当格式化HDFS后，执行bin/hadoop fs -ls /，出现

$ bin/hadoop fs -ls /
13/12/28 11:38:22 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8888. Already tried 0 time(s).
13/12/28 11:38:24 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8888. Already tried 1 time(s).
13/12/28 11:38:26 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8888. Already tried 2 time(s).
13/12/28 11:38:28 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8888. Already tried 3 time(s).
13/12/28 11:38:30 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8888. Already tried 4 time(s).
13/12/28 11:38:32 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8888. Already tried 5 time(s).
13/12/28 11:38:34 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8888. Already tried 6 time(s).

可以编辑conf/core-site.xml文件，更改其中的端口号8888为其他端口号例如9000，然后再重新格式化即可。